What is causing this??? I changed plugs today no diference. Car starts everytime but 2 min after cold start it shakes. Engine light on all the time. Please help!!

to NICO!

Code 34 is a knock sensor code. The knock sensor is basically a little microphone that is bolted on to the engine's head that listens for spark knock. If it detects it, the ECU retards the timing advance to try to control it. In the event that the ECU detects that the sensor is not functioning, the timing advance is retarded as much as the ECU can to protect the engine. Typically this failure is detected as "something doesn't feel quite right" but it's not something as obvious as you describe.

Code 51 is an injector code. From what I can tell, the ECU is detecting a resistance problem from one of the injectors - either due to a problem in the wiring or a problem with the injector.

Please download your factory service manual (the oldest one available is the '94) and you can research how to ohm test your injectors with a multimeter. They should ohm out at about 12 ohms each. It's available at http://www.nicoclub.com/FSM/J30/

A dead miss on a cylinder would certainly fit your shake at idle, and running on 7 cylinders would definitely make the car accellerate more slowly. It's possible that the injector still functions while cold - but it's more likely that you just don't feel the shake as well because the idle speed is higher when the engine is cold.

Good luck!

Heath

That sounds like it might work, ill check it out today and get back to you. I actualy have the original service manuel that came with the car so ill use that. Ill give it a shot and get back to you.

So I want to thank you for your help. This morning I went to autozone to see how much an ohm reader would cost, it was like 25 so I figured I would wait to borrow one from a friend. I did however buy lucus fuel injector cleaner that cost like 5bucks. Two hours after driving the car the check engine light went off and the car stopped shaking, it excelerates great now. Thank you so much, this site is great!!!!!

I hope that fixes it for good! I would still look for a meter. If you have a Harbor Frieght store nearby - www.harborfreight.com - they have them really cheap. Again, not the best available, but typically good enough for our purposes. Injector failure (electrically) isn't common on the J30, at least that I'm aware of, but from what I could tell the code you had indicated a failure that shouldn't have been fixed by injector cleaner.

Heath